Fix System UI Tests so they don't read flags before setting them.

This is in preparation of using SetFlagsRule.ClassRule on SysuiTestCase
* Change many tests which construct fixtures during class initialization to use lazy instead.
* Change many tests to use @EnableFlags and @DisableFlags instead of the SetFlagsRule methods.
* Mark some tests as @BrokenWithSceneContainer which were only passing because of this error.

Fixes: 336768870
Flag: TEST_ONLY
Test: atest SystemUITests
Test: atest SystemUiRoboTests
Change-Id: Ie1bc2fead8c86f4a5b52b179e10fbbc1314d7ebc